FR3046407A1 - FIXED CYLINDER DEVICE FOR SYSTEM FOR CONTROLLING THE ORIENTATION OF BLOWER BLADES OF A TURBOMACHINE - Google Patents

Abstract

The invention relates to a device with a fixed cylinder for a control system (2) for the orientation of the fan blades of a turbomachine, comprising a cylinder body (22) housed inside an annular housing (20). of the turbomachine forming a bearing support, said casing being centered on a longitudinal axis (XX) of the turbomachine and inclined with respect thereto, the cylinder body comprising an internal volume in which is able to slide a synchronization ring ( 30) separating the internal volume into two chambers insulated from each other, and a plurality of cylinder rods (42) passing through the bearing support housing and each having an end secured to the synchronization ring and an end opposed to be connected to an inner ring (14) of a motion transfer bearing (10) to drive in translation.

Description

Background of the invention

The present invention relates to the general field of turbomachines equipped with one or two fan (s) ducted (s) or not careened (s), and more particularly to the control of the orientation of the fan blades (s) of these turbomachinery.

A preferred field of application of the invention relates to propeller (s) turbojets, for example the "Open Rotor" in English, which comprise two contra-rotating propellers placed downstream ("pusher" version in English) or upstream (version "Puller" in English) of the gas generator. However, the invention also applies to turboprop engines with one or more propellant propellers and turbine engines with faired blower.

In a propeller-driven turbojet engine, it is known that the orientation (or wedging) of the blades that form these propellers constitutes one of the parameters making it possible to manage the thrust of the turbojet engine, in particular by still operating the propeller in the propellers. best conditions possible. Indeed, the speed of the propellers is almost constant on all phases of operation, and it is the pitch of the propeller blades that varies the thrust. Thus, in the cruising flight phase, it is sought to obtain the lowest power possible on the turbine shaft which is necessary for a given traction at a given speed of the airplane, so as to obtain the best efficiency ( that is, the efficiency to minimize fuel consumption and increase the range. Conversely, on takeoff, the strongest possible traction is sought to accelerate and then take off the plane.

Various systems for controlling the orientation of the blades of the propellers of the turbojet can be envisaged. One of the known systems provides for the use of an axial jack, connected to a fixed reference (with respect to the structures of the turbojet engine) and centered on a longitudinal axis thereof. Typically, the outer body of this cylinder is connected to the inner ring of a transfer transfer bearing (called LTB for "Load Transfer Bearing") to perform a translational movement while ensuring the passage of the fixed reference (the cylinder) at the rotating mark (of the propeller). As for the outer ring of the bearing, it is connected to rods, themselves connected to the blades of the propeller to achieve their rigging. In particular, reference may be made to the document WO 2013/050704 which describes an exemplary implementation of such a system.

Another known system for controlling the orientation of the propeller blades of the turbojet engine provides for the use of a rotary cylinder, that is to say, rotating relative to the fixed reference of the turbojet engine. Typically, the cylinder is connected to fingers, which are themselves connected to the blades of the propeller. These fingers thus perform a combined movement of rotation and translation to describe a helical pattern around the longitudinal axis of the turbojet engine.

However, these control systems have certain disadvantages. Indeed, the control system using a rotary cylinder is relatively complex to implement, particularly with regard to the effect of centrifugation of the oil in the cylinder chamber for which it is difficult to anticipate the unbalance caused by this rotation. In addition, the precision of blade pitch obtained by this system is uncertain. As for the control system using a fixed jack, it has the main disadvantage of occupying an important position in the radial direction. However, certain architectures of non-ducted fan turbojet engine have a low availability (in the radial direction) to accommodate the fixed cylinder of their control system of the orientation of the blades. This is particularly the case for turbojet engines whose hub ratio is low.

Object and summary of the invention

The present invention therefore has the main purpose of providing a cylinder device for control of the orientation of the blades which does not have the aforementioned drawbacks.

According to the invention, this object is achieved by means of a device with a fixed jack for a system for controlling the orientation of the fan blades of a turbomachine, comprising: a cylinder body housed inside an annular casing of the turbine engine forming a bearing support, said casing being centered on a longitudinal axis of the turbomachine and inclined with respect thereto, the cylinder body comprising an internal volume in which is able to slide a synchronization ring separating the internal volume in two rooms isolated from each other; and a plurality of jack rods extending through the bearing support housing and each having an end secured to the synchronization ring and an opposite end for connection to an inner ring of a motion transfer bearing to drive it. in translation.

The device according to the invention uses an annular housing of the turbine engine forming a bearing support for housing the body of the cylinder. To support the shaft of the rotating propeller, it is necessary to have two bearings sufficiently spaced from each other to meet dynamic resistance criteria. These bearings are typically held by an annular housing of the turbine engine forming a bearing support. For this housing to be sufficiently rigid while having a thickness (and therefore a mass) limited, it is generally inclined relative to the longitudinal axis of the turbomachine (for example at least 30 °), which gives it a conical shape. The invention is here remarkable in that it uses the unused volume inside this bearing support housing to house the cylinder body. As the body of the control cylinder of the orientation of the fan blades generally has a relatively large axial size (typically at least twice the stroke of the cylinder), the fact of housing this fixed part of the jack inside the Bearing support housing provides a very small control system. In addition, the control system obtained has relatively few parts (which makes it lighter) and has a great simplicity in terms of operation and assembly.

Preferably, the bearing support housing comprises an outer ring of a rolling bearing which is offset radially inwardly relative to the cylinder body and which is intended to guide a rotating ring in rotation.

The internal volume of the cylinder body can be closed, upstream by a wall provided with a plurality of holes through which the cylinder rods, and downstream by a hood. In this case, the cover can be fixed on the cylinder body by means of a plurality of screws distributed around the longitudinal axis of the turbomachine. Similarly, the cover may comprise slots intended to cooperate with jaw of the cylinder body so as to seal the internal volume of the cylinder body.

Also preferably, the wall closing upstream the internal volume of the cylinder body forms a single piece with the housing bearing support housing (the cylinder rods are mounted by the open side of the housing bearing support housing, c that is to say downstream, which requires that the internal volume is closed downstream by a removable cover). As for the cylinder rods, they can be fixed to the synchronization ring of the chamber by means of nuts screwed onto the downstream end of the rods and are advantageously regularly distributed around the longitudinal axis of the turbomachine. The subject of the invention is also a system for controlling the orientation of the fan blades of a turbomachine, comprising at least one set of adjustable-orientation fan blades, said assembly being rotatably connected to a rotating ring, the fan blades being coupled, for adjustment of their orientation, to a motion transfer bearing for pivoting fan blade pivots about their radial axis, said motion transfer bearing comprising an inner ring connected to a device as defined above. The subject of the invention is also a method of mounting the device as defined above, comprising, from a propeller shaft previously mounted on a main casing of the turbomachine by means of a rolling bearing, the assembly of the cylinder rods and the synchronizing ring on the cylinder body housed inside the bearing support housing, and the assembly of this assembly on the main casing of the turbomachine and the shaft of propeller. Such a mounting method has the advantage of having an assembly already mounted that is brought to the main housing and the propeller shaft. The number of steps of the assembly can thus be reduced, which simplifies and fluidifies considerably these assembly operations.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the present invention will emerge from the description given below, with reference to the accompanying drawings which illustrate an embodiment having no limiting character. In the figures: - Figure 1 is a sectional view in its environment of a fixed cylinder device according to the invention; FIG. 2 shows in more detail the structure of the chamber of the device of FIG. 1; and FIG. 3 is a partial perspective view of the device of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION The invention applies to any turbomachine equipped with at least one ducted or non-ducted fan, and whose propeller blades (in the case of a non-ducted fan) or the fan blades. (in the case of a streamlined fan) are equipped with a change of pitch system. The invention applies in particular to turboprop engines with one or more propeller propellers, as well as propeller (s) (known as "Open Rotor") turbojet engines which comprise a propeller (and a variable-pitch stator for the propeller). USF - "Unducted Single Fan", or "single fan unsheathed") or two contra-rotating propellers placed upstream (in "puller" version in English) or downstream (in "pusher" version in English) of the gas generator. The invention is still applicable to streamlined fan turbomachines. The architecture of these types of turbomachines is well known to those skilled in the art and will not be described here in detail. Briefly, these turbomachines comprise one or more propellers (in the case of a non-ducted fan turbomachine) or a fan (in the case of a fan-cooled turbomachine) each consisting of a set of blades (or blades ) blowers variable pitch angle, that is to say that their orientation can be changed by means of a control system of the orientation of the blades described below.

FIG. 1 partially represents an example of a control system 2 for the orientation of the blades of a helix of a non-ducted fan-shaped turbomachine according to the invention. Of course, in the case of a streamlined fan turbomachine, the principle of the invention described hereinafter applies in the same way to the fan blades.

This control system 2 comprises a rotary ring 4 (or hub) centered on longitudinal axis X-X of the turbomachine and provided with orifices 6 through which are mounted the pivots 8 of the fan blades (not shown in the figures).

Each pivot 8 is coupled, for adjusting the orientation of the corresponding blade, to a motion transfer bearing 10 (also called LTB for "Load Transfer Bearing") for pivoting said pivot about its radial axis Z-Z. For this purpose, the motion transfer bearing 10 comprises an outer ring 12 and an inner ring 14, these rings 12, 14 being centered on the longitudinal axis XX of the turbomachine, movable in translation along this axis XX, and defining bearing tracks for bearings (here two rows of balls 16 to angular contact to transmit axial forces in both directions).

The outer ring 12 of the motion transfer bearing is coupled, directly or indirectly, to an inner radial end of the pivots, for example by means of lever arms 18. When the inner ring of the motion transfer bearing moves axially under the actuating a jack device, it pivots the lever arms and thus the pivots 8 in the orifices 6 of the rotary ring about their radial axis ZZ, thereby causing a pivoting of the fan blades.

Upstream of the jack device, the turbomachine also comprises a main casing 19 carrying a ball bearing 21 intended to support in rotation the propeller shaft 23 which supports the rotary ring 4 This propeller shaft 23 is preferably driven by a turbine and a reducer (not shown in the figures).

On this main casing 19 is fixed an annular casing 20 centered on the longitudinal axis XX of the turbomachine and inclined relative thereto by an angle generally greater than 30 ° (this inclination being oriented so as to give the casing 20 a cone shape open downstream).

Typically, this casing 20 serves as a support for a rolling bearing 24 intended to guide in rotation the rotary ring 4. For this purpose, the casing 20 carries the outer ring 24a of the rolling bearing 24 (whose inner ring 24b is secured to rotating ring 4). In addition, the casing 20 and the rotary ring 4 delimit between them an oil enclosure 25 enclosing the jack device. This oil chamber 25 is pressurized in depression so that the oil does not escape. To limit leakage rates out of the chamber, it is in particular provided to have a seal 27 upstream of the pivots of the fan blades, between a downstream casing 23a of the propeller and the main casing 19. Leaks are possible at the orifices 6 of the rotary ring 4 in which are mounted the pivots of the fan blades. These leaks are, however, compensated for by the sealing of the oil enclosure. Furthermore, this oil chamber 25 extends downstream of the rolling bearing 21 and can contain a reducer and seals between the various shafts.

According to the invention, the jack device intended to ensure pivoting of the fan blades comprises in particular an annular jack body 22 which is centered on the longitudinal axis XX of the turbomachine and which is housed inside the space delimited by the casing 20 forming a bearing support.

The cylinder body 22 forms a single piece with the casing 20 and delimits an internal volume inside which is able to slide a synchronization ring 30 separating the internal volume of the cylinder body into two isolated chambers, one of the other, namely an upstream chamber 22a and a downstream chamber 22b.

This synchronizing ring 30 plays the role of piston being able to slide inside the internal volume of the cylinder body under the effect of a hydraulic fluid (not shown) injected under pressure into one or the other upstream and downstream chambers.

The internal volume of the cylinder body 22 is closed upstream by a wall 26 provided with a plurality of holes 28 distributed around the longitudinal axis X-X of the turbomachine (FIG. 2). This wall 26 may advantageously form a single piece with the housing 20 forming a bearing support.

At its end opposite the wall 26 (that is to say downstream), the internal volume of the cylinder body is closed by a cover 32. Here, the cover 32 is an independent part of the housing 20 which has a crown shape screwed on it. For this purpose, the housing and the cover each have holes, respectively 34 and 36, which are regularly distributed around the longitudinal axis XX of the turbomachine (for example at their outer periphery) and which are traversed by screws (not shown in the figures).

In addition, in order to ensure a tightness of the internal volume of the cylinder body (and avoid any inadvertent opening thereof under the effect of the high pressure in the chambers 22a, 22b), it comprises, for example at the level of its inner periphery, jaws 38 cooperating with crenellations 40 corresponding to the cover 32 so as to ensure a tightness of the internal volume of the cylinder body in which there is a significant oil pressure.

Of course, other means can be envisaged to ensure attachment of the cover 32 to the cylinder body 22.

As also shown in FIG. 3, the jack device according to the invention also comprises a plurality of jack rods 42 which are mounted through the holes 28 of the wall 26 of the jack body. These cylinder rods are preferably regularly distributed around the longitudinal axis X-X of the turbomachine to match the need for stall force. The number of cylinder rods is a compromise between the effort to be passed in each rod directly affecting the section of each rod and the number of rods affecting the weight of the system. Preferably there are at least 4 rods to distribute the forces on the piston.

Each cylinder rod 42 has a downstream end which is attached to the synchronization ring 30 of the cylinder body and an upstream end which is connected to the inner ring 14 of the motion transfer bearing 10 to drive it in translation.

The fixing of the cylinder rods on the synchronization ring can be done by means of nuts 44 which are clamped on the downstream end of the rods, the latter being threaded.

Similarly, at their upstream end, the cylinder rods 42 are connected to the inner ring 14 of the motion transfer bearing by means of screws 46 extending in a radial direction (Figure 1).

The operation of the jack device according to the invention is evident from the foregoing. In order to adjust the orientation of the pivots of the fan blades 8, hydraulic fluid is injected under pressure into one or the other of the upstream and downstream chambers 22a, 22b of the chamber, which causes a displacement of synchronization ring 30 following longitudinal tax XX of the turbomachine. The rods 42 then translate axially in a synchronized manner so as to move the transfer-motion bearing 10 upstream or downstream. In turn, this translation of the bearing causes a pivoting of the lever arms 18 resulting in a synchronized pivoting of the fan blades.

The mounting of the cylinder device according to the invention is as follows. In a first step, the propeller shaft 23 is assembled to the gearbox and the rolling bearing 21 (and its support) to the main casing 19 of the turbomachine. The cylinder rods 42 and the synchronizing ring 30 are then assembled on the cylinder body 22 and the housing 20 forming a bearing support. The assembly formed by the jack rods, the synchronizing ring, the cylinder body, the bearing support housing and the rolling bearing 24 can then be brought axially from upstream to downstream to assemble it. on the main casing 19 of the turbomachine and the propeller shaft 23. The motion transfer bearing 10 is then assembled with the cylinder rods 42. The downstream casing 23a of the propeller is then assembled with the rotary ring 4 and the pivots of the fan blades are mounted on this downstream casing. The lever arms 18 and the pivot studs of the fan blades are added to link the pivots to the motion transfer stage. Finally, an upstream propeller casing 23b is assembled 23c to the propeller shaft 23 by means of a splined connection and to the rotary ring 4. Disassembly of the cylinder device is carried out in the opposite direction.

Claims (10)

1. Device with fixed jack for a control system (2) for the orientation of the fan blades of a turbomachine, comprising: a cylinder body (22) housed inside an annular casing (20) of the turbomachine forming a bearing support, said casing being centered on a longitudinal axis (XX) of the turbomachine and inclined with respect thereto, the cylinder body comprising an internal volume in which is able to slide a synchronization ring (30) separating the internal volume into two isolated chambers one from the other; and a plurality of jack rods (42) extending through the bearing support housing and each having an end secured to the synchronization ring and an opposite end for connection to an inner ring (14) of a transfer bearing movement (10) to drive it in translation. The device according to claim 1, wherein the bearing support housing comprises an outer ring (24a) of a rolling bearing (24) which is offset radially inwardly relative to the cylinder body (22) and which is intended to guide in rotation a rotary ring (4). 3. Device according to one of claims 1 and 2, wherein the internal volume of the cylinder body is closed, upstream by a wall (26) provided with a plurality of holes (28) through which the rods cylinder, and downstream by a hood (32). 4. Device according to claim 3, wherein the cover (32) is fixed on the cylinder body by means of a plurality of screws distributed around the longitudinal axis of the turbomachine. 5. Device according to one of claims 3 and 4, wherein the cover (32) comprises crenellations (40) for cooperating with jaw (38) of the cylinder body so as to seal the internal volume of the body of cylinder. 6. Device according to any one of claims 1 to 5, wherein the cylinder rods (42) are fixed to the synchronization ring (30) by means of nuts (44) screwed on the downstream end cylinder rods. 7. Device according to any one of claims 3 to 6, wherein the wall (26) closing upstream the internal volume of the cylinder body forms a single piece with the housing bearing support housing. 8. Device according to any one of claims 1 to 7, wherein the cylinder rods (42) are regularly distributed around the longitudinal axis of the turbomachine. 9. Control system (2) for the orientation of the fan blades of a turbomachine, comprising at least one set of controllably adjustable fan blades, said assembly being rotatably connected to a rotary ring (4), the fan blades being coupled, for the adjustment of their orientation, to a motion transfer bearing (10) for rotating pivot pins (8) of fan blades about their radial axis, said motion transfer bearing comprising a internal ring (14) connected to a device according to any one of claims 1 to 8. 10. A method of mounting the device according to any one of claims 1 to 8, comprising, from a propeller shaft (23) previously mounted on a main casing (19) of the turbomachine via a rolling bearing (21), the assembly of the cylinder rods (42) and the synchronizing ring (30) on the cylinder body (22) housed inside the bearing support housing (20) , and the assembly of this assembly on the main casing (19) of the turbomachine and the propeller shaft (23).